A typical marine outboard engine has an internal combustion engine for propelling the marine outboard engine. Fuel is delivered to fuel injectors in the engine via a fuel system that has one or more fuel pumps and a fuel vapor separator. A fuel pump draws fuel from a fuel tank and supplies it to the fuel vapor separator when fuel in the fuel vapor separator drops below a certain threshold. Another fuel pump delivers fuel from the vapor separator to the fuel injectors.
Not all the fuel pumped to the injectors is consumed by the internal combustion engine. A portion of the fuel pumped to the injectors is allowed to flow past the fuel injectors, which aids in cooling the fuel injectors. This fuel is returned to the fuel vapor separator.
The fuel returned from the injectors is typically warmer than fuel delivered to the fuel vapor separator from the fuel tank. Such returned fuel is therefore more volatile than cooler fuel, and may be foamy. Fuel in the fuel vapor separator, and especially the warmer fuel in the fuel vapor separator, produces fuel vapor. Fuel vapor is typically vented from a top part of the fuel vapor separator to the internal combustion engine's air intake, where it is consumed during the internal combustion engine's operation.
Some vapor separators have cooling lines running through the fuel often in spirals or some other shape with large surface contact areas to cool as much of the fuel as possible. If a marine outboard motor is to be cooled using the water surrounding the watercraft, complicated cooling lines can be susceptible to clogs or similar issues if debris from the water source enters the cooling lines. These complicated cooling line forms can further be difficult to manufacture.
Therefore, there is a desire to reduce the temperature of the fuel in the fuel vapor separator without at least some of the inconveniences described above.